Diagnostic system and method for an electric motor using torque estimates
AssigneeFord Global Technologies, LLC
InventorsMathew Boesch, Vijay Garg, Abbas Raftari
Life of this patent
Estimating the term…
Abstract
A system and method for diagnosing a potential electrical operating discrepancy in a polyphase electric motor by generating two independent torque estimates using a plurality of current sensors and, optionally, a shaft position sensor. Differences between the independent torque estimates are used to indicate potential discrepancies in electrical operating characteristics of the motor.
Claims14
A diagnostic system for a polyphase electric motor with n phases, the system comprising:
- a first subsystem to determine first currents of each motor phase;
- a second subsystem to determine a first value of motor shaft position;
- a third subsystem to estimate a first value of motor torque using the first currents and the first value of motor shaft position;
- a fourth subsystem to determine second currents of each motor phase;
- a fifth subsystem to determine a second value of motor shaft position;
- a sixth subsystem to estimate a second value of motor torque, independent of the first estimate of motor torque, using the second currents and the second value of motor shaft position;
- and
- a comparator system to compare the first and second estimates of motor torque.
A method to diagnose potential discrepancies in electrical operating characteristics of a polyphase electric motor comprising the steps of:
- determining a first set of currents for each motor phase with n−1 first current sensors, where n is any number of phases greater than one;
- determining a first value of motor shaft position;
- estimating a first value of motor torque using the first value of motor shaft position and the first set of currents;
- determining a second set of currents for each motor phase with n−1 current sensors;
- determining a second value of motor shaft position;
- estimating a second value of motor torque, independent of the first estimate of motor torque, using the second value of motor shaft position and the second set of currents;
- and
- comparing the first and second estimates of motor torque.
A controller in a system for diagnosing potential discrepancies in electrical operating conditions in a polyphase electric motor, the controller comprising:
- a sub-system (172, 152, 154, 156, 158) to determine current in each motor phase;
- a sub-system (182, 190) to determine first values of motor shaft position;
- a sub-system (67, 176, 178) for generating a first estimate of motor torque using the current in each motor phase and the first value of motor shaft position;
- a sub-system (182, 190) to determine a second value of motor shaft position;
- a sub-system (67, 190, 114) for generating a second estimate of motor torque using current in each motor phase and a second value of motor shaft position;
- and
- a sub-system (67) for comparing the first and second estimates of motor torque for discrepancies whereby a motor operator can be notified of a potential discrepancy in electrical operating characteristics.
Dependencies are inferred from the claim text.